This invention relates to a process for producing a glycol monoether by reacting an acetal or by reacting aldehyde and alcohol with carbon monoxide and hydrogen in the presence of a novel catalyst.
Glycol monoethers have a wide variety of applications as solvents and reaction media. In the prior art, glycol monoethers are commercially produced by preparing an olefin oxide from an olefin and adding a suitable alcohol thereto. Such conventional methods use an olefin, which is a petroleum product, as the starting material. The recent problems of cost and supply by the petroleum chemical industry has caused reconsideration of these methods of production, and research has been carried out seeking a new method of producing glycol monoethers from a starting material other than an olefin.
Among these new methods is the reaction of an acetal with carbon monoxide and hydrogen in the presence of a cobalt carbonyl catalyst (West German Pat. Nos. 875,802 and 890,945). This method, however, suffers from the disadvantage of low selectivity of the glycol monoether. In addition, since the cobalt carbonyl is inevitably decomposed when the glycol monoether is separated from the reaction product by distillation, the catalyst cannot be recycled.
It has been found that cobalt carbonyl combined with a trivalent organic phosphorus compound such as tertiary phosphine or a bidentate chelate ligand containing nitrogen or oxygen can improve the selectivity of the glycol monoether to a considerable extent. In addition, such a combination can stabilize the catalyst so that it can be recycled without complicated catalyst recovery and regeneration. This is possible because no decomposition takes place during separation of the glycol monoether from the reaction product by distillation.